An example and conventional antenna apparatus which tracks radio waves from a communication counterparty to change the direction of an antenna is provided with a counter weight at the antenna-apparatus side of a base plate and a vibration isolation structure between the counter weight and the base plate (see, for example, Patent Literature 1). Moreover, there is a communication antenna apparatus having an AZ (azimuth)/EL (elevation) two-axis drive antenna or an AZ/cross-EL/EL three-axis drive antenna which ensures fixing of an antenna unit at the time of detaching a unit to improve the serviceability (see, for example, Patent Literature 2).
Regarding the placement of the counter weight, like the antenna apparatus disclosed in Patent Literature 1, it is apparent that both the antenna and the counter weight are provided at the same side of the base plate (see, for example, Patent Literatures 3 and 4). As disclosed in Patent Literature 5, an antenna apparatus, in which a counter weight is embedded to the lower end of its antenna, has a pivot located at the middle of the antenna and the antenna is provided to be able to rotate around the pivot. As a vibration isolation structure of an antenna apparatus, a helical isolator disclosed in, for example, Patent Literatures 6 to 8 is often used.